Method and apparatus for measuring and monitoring torque exerted during pedalling of a bicycle or the like equipment

ABSTRACT

An apparatus for measuring and monitoring the torque exerted by a cyclist during pedalling of a human-powered machine, as for example a bicycle, includes a cartridge or the like which is adapted, in use, to be releasably retained within a hollow spindle ( 101 ) of the machine, and one or more sensor elements ( 110, 120, 130 ) for progressively sensing and generating signals, during rotation of a crankshaft of the machine, which are indicative of the angular position of the or each crank arm ( 63 ) of the machine and/or the torque applied thereto. The apparatus allows for measuring and monitoring both in the direction of, and against the direction of, pedalling of the cyclist.

FIELD OF THE INVENTION

The present invention relates, in general terms, to an apparatus for determining/measuring the torque exerted on a body of revolution which is capable of being driven rotatably about an axis of rotation. More particularly, but not exclusively, the invention relates to an apparatus and means for measuring/recording the torque applied by a cyclist during the pedalling of a bicycle, and especially a bicycle of the type the subject of the present applicant's U.S. patent application Ser. No. 11/696,516.

What are referred to as power measurement devices, for use on or with a bicycle, typically may fall into one of two basic categories, firstly devices that measures torque and/or angular velocity in driving components of the bicycle, such as for example pedals, crank arms and bottom bracket, and secondly devices that measure torque and angular velocity in driven components of a bicycle, such as for example the chain rings, chain, rear wheel hub and rear wheel.

The present applicant's U.S. patent application Ser. No. 11/696,516 describes and defines an improved bicycle or the like for which the apparatus the subject of the present invention is particularly suited. That earlier International Patent Application relates to a mechanism which allows limited movement of the respective left and right crank arms of a given bicycle relative to the chain rings, whereby to accentuate and allow for more ready identification of what are referred to as “dead zones” in the pedalling of the cyclist. In that regard, and by way of further explanation, a “dead zone” may be defined as or considered to be that arc (degree of angular movement) in the pedalling of a cyclist during which no torque whatsoever is being applied to the crank arm which contributes to propelling the cyclist in the forward direction. The onset of a “dead zone” can be due to a variety of reasons, including tiredness of the cyclist, inefficiencies in the pedalling action of the cyclist, etc. With the arrangement of the same earlier Application the cyclist will feel or sense the limited movement associated with such a “dead zone” through the pedals and will respond to that feeling or sensation by the application of additional torque to the relevant crank arm. With repetition and continued practice, the cyclist's muscles will become better trained/toned, with the consequent result of the pedaling action becoming more smooth and powerful, with the effects of the “dead zones” being minimized, if not removed altogether, and with both left and right legs of the cyclist being properly synchronised in the application of the desired torque to the pedals.

Measurement of what shall herein be referred to as the pedalling power of a cyclist can be a useful tool, in terms of detection of inefficiencies in cycling techniques and in ultimately achieving better, if not peak, performance. However, what are referred to as bicycle power meters, of the type currently available, for measuring such pedaling power, can only measure the power being generated by one leg of the cyclist or, as an alternative, the combined power generated by both legs. Presently known and in use power meters are unable to separately measure the power generated by each leg of the cyclist independently. Certainly there exist some power meters which enable subsequent down-loading of measured data to a personal computer or the like associated with the cyclist or the bicycle, which can then utilise an appropriate computer program to predict, rather than measure, the individual power contributed to the pedalling action by each leg in isolation. In all real respects, however, there does not currently exist a power meter which, on a personal or bicycle computer, can display actual as distinct from predicted individual leg power.

THE PRIOR ART

Schroberer (PCT/EP88/00601) describes an arrangement wherein the force exerted on the crank arm is transferred to the chain ring spider via a deformation element. The deformation of the deformation element and the angular velocity of the crank arm are converted to electrical signals, which are electronically multiplied to give power. The deformation of the deformation element is measured by means of strain gauges, and the angular velocity is derived from the time it takes for the crank arm to effect a complete revolution, then dividing this by 2π radians. Over one crank revolution angular velocity and torque can vary quite significantly. Therefore, integrating the torque over one crank revolution to calculate the average power is not very accurate. Furthermore, to mount the Schroberer power meter to a bicycle requires the replacement of the crankset with a specifically built crankset that incorporates the power meter. The replacement must be done by a reasonably skilled mechanic with specific tools for the job.

In addition, Schroberer measures the combined power generated by both legs in the forward pedalling direction only.

Another method of measuring pedalling power on a bicycle is described in U.S. Pat. No. 6,418,797 of Ambrosina and Pawelka, wherein a hub of the driven wheel of the bicycle includes one or more components such as an inner hub member, an outer hub member and a linking member which couples the rotational torque through the wheel, thereby to rotate the wheel. Sensing means, such as one or more strain gauges, are mounted on the linking member such that strain in the linking member is detected and measured. A sensor in the hub detects each complete revolution of the hub, and angular velocity is derived by dividing the time it takes per revolution by 2π radians. Because power is calculated only once per hub revolution the measurement of output, which is the total power generated by both legs in the forward direction only, is not very accurate. To mount the Ambrosina/Pawelka power meter system requires the replacement of the rear wheel with a specifically built rear wheel that has the power meter incorporated in the hub.

A further method of measuring pedalling power is described in Gerlitzski U.S. Pat. No. 6,356,847, which relates to a method and device for determining torque exerted on a body of revolution capable of being driven rotatably about an axis of rotation. The device therein possesses first and second measurement generators which are arranged on the body of revolution, each with a respective measurement transducer supplying a square-wave output signal in direct response to the measurement generator. With torque applied to the body of revolution that the body of revolution will twist, causing the square-waves to become out of phase. The torque is determined from the distance between the edges of the first and second measurement transducer square-wave signal. This method and device is incorporated in the bottom bracket of the crankset and mounted in the bicycle frame, where the body of revolution is the crank spindle. The angular velocity of the crank spindle is measured several times per crank revolution in this realisation.

In a conventional bicycle the right hand crank arm has the chain ring spider immovably fixed thereto it. Therefore in Gerlitzski it is only the power produced by the left leg that causes deformation of the body of revolution and hence the power calculated from the torque produced and the angular velocity is not truly representative of the total power from both legs.

In addition, to mount the Gerlitzski power meter to a bicycle requires the replacement of the bottom bracket with a bottom bracket specifically built with the power meter incorporated. The replacement must be done by a reasonably skilled mechanic with specific tools for the job.

In Polar Electro European Patent 0909940A2, a method and apparatus is described for measuring power output by measuring the speed and tension of the bicycle chain. The apparatus includes a chain speed sensor, a chain tension sensor and electronic processing means to calculate and display the power output based upon the chain measurements.

The tension of the chain is derived from measuring its vibration frequency. However the vibration frequency is dependent on a number of variables, for example the age of the chain and the angle of the chain from the chain ring to the rear sprocket. Therefore the calculated power is not very accurate and only represents power in the forward pedalling direction.

To mount the Polar Electro power meter requires the replacement of one of the jockey wheels on the rear derailleur to measure chain speed, accurate mounting of the chain tension sensor on the chain stay of the bicycle frame and measurement of the length of the chain from the chain ring to the rear sprocket.

Each of the abovementioned prior art devices has been commercialised and widely used in the cycling market. Each includes a bicycle computer that is mounted on the handlebar with a screen which displays power (amongst other common measurements such as time, cadence, heart rate, odometer, distance, and speed). Software for a personal computer is also included as part of these power meter systems and is used to analyse data that has been recorded by the bicycle computer during the ride. The data is downloaded to the personal computer after the ride and the software has a number of functions to help the cyclist interpret the data to assess and improve performance.

The present invention seeks to overcome the problems associated with the prior art by providing a power measuring apparatus which allows for measurement, accurately for display, of torque generated by both legs of the cyclist, in either the direction of pedalling or against that direction. The arrangement in accordance with the present invention is further adapted to be readily incorporated in an existing bicycle, as for example of the type described in the present applicant's U.S. patent application Ser. No. 11/696,516, by even the unskilled person without the need for any special tooling and/or training.

In accordance with one aspect of the present invention there is provided an apparatus for measuring and monitoring the torque exerted by a cyclist during pedalling of a human-powered machine, said apparatus including a cartridge or the like adapted, in use, to be releasably retained within a hollow spindle of said machine said apparatus further including one or more sensor elements for progressively sensing and for generating signals, during rotation of a crank shaft of said machine, which signals are indicative of the angular position of the or each of said machine crank arm and/or the torque applied thereto.

In accordance with a further aspect of the present invention there is provided a method for measuring and monitoring, during pedalling of a bicycle or the like human-powered machine, the torque exerted by the cyclist during said pedalling, including providing said bicycle with an apparatus, to be releasably associated with a hollow crank spindle of said bicycle, including sensing means for generating signals indicative of the angular position of the or each said crank arm of said bicycle during rotation thereof, and the torque applied to the or each crank arm during pedalling.

With the apparatus, power transfer mechanism and method as set out in the preceding paragraphs, torque may be measured and monitored either in the direction of, or against the direction of, pedalling of the cyclist.

DESCRIPTION OF THE DRAWINGS

In order that the invention may be more clearly understood and put into practical effect there shall now be described in detail preferred constructions of a power measuring apparatus for a bicycle in accordance with the invention. The ensuing description is given by way of non-limitative example only and is with reference to the accompanying drawings, wherein:

FIG. 1 is a side view of a first embodiment of a crank spindle for a bicycle, to be utilised in accordance with the invention;

FIG. 2 is an exploded view of an assembly to be employed for mounting the crank spindle of FIG. 1 within the frame of a bicycle;

FIG. 3 is a side view of an assembled crank spindle assembly, adapted then to be located within the frame of a bicycle;

FIG. 4 is a sectional view of a power meter cartridge in accordance with the invention, for insertion in the spindle of FIG. 1;

FIG. 5 provides close-up views of certain of the components of the power meter cartridge of FIG. 4.

FIG. 6 is a schematic representation of preferred electrical/electronic circuitry for the power meter cartridge of FIG. 4;

FIG. 7 is an exploded view of further components, adapted in use to be associated with the assembly of FIG. 3;

FIG. 8 is a sectional view of the power meter cartridge of FIG. 4 as located within the spindle of FIG. 1;

FIG. 9 is a sectional view of an assembly in accord with the invention, mounted on crank spindle bearing adapters;

FIG. 10 is an overview of all components of the apparatus in accordance with the invention, assembled relative to crank arms of a bicycle, but within the bicycle frame itself (not shown);

FIG. 11 is a side view of an alternative embodiment of a crank spindle for a bicycle in accordance with the invention;

FIG. 12 is an exploded view of an assembly to be employed for according the crank spindle of FIG. 11 within the frame of a bicycle;

FIG. 13 is a sectional view of an assembly of the crank spindle of FIG. 11, chain ring spider, right crank arm and securing flange;

FIG. 14 is a sectional view taken along the line A-A in FIG. 13; and

FIG. 15 is a schematic representation of the torque sensors and dogs depicted in a two-dimensional plane, and also shows the associated connection of the torque sensors in a transducer bridge configuration.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference now to the drawings, there are shown therein arrangements in accordance with the invention, made up of a number of elements assembled together (as described in more detail later), as they would be located on and extend through a bicycle frame (not shown). As previously pointed out, the power measuring device/apparatus in accordance with the present invention is particularly, although not exclusively, suited for use with a power transfer mechanism of the type described and defined in the present applicant's U.S. patent application Ser. No. 11/696,516. It should be understood, however, that under no circumstances is the apparatus in accordance with the present invention to be considered limited to use in such a context or apparatus.

FIG. 1 is an exploded view of an assembly adapted to receive and releasably retain a power measuring device in accordance with the present invention. As illustrated the assembly includes a hollow crank spindle 1, adapted in use to be associated with/connected to (in any known manner) opposed crank arms 63, 64 (see FIG. 10) of a given bicycle. The hollow spindle 1 includes thereon, at a location spaced from the right hand free end thereof, an integral and peripheral flange 5 which is adapted, in use, to assist in location of the spindle 1 relative to the right hand spindle bearing adapter 59 (see FIG. 9) itself. At the other end of the crank spindle 1 there will be provided a splined section 2, to which the left hand crank arm 64 may be attached in any suitable manner and using any known means. The flange 5 includes, at a plurality of positions spaced around the circumference/periphery thereof, a plurality of dogs or the like protrusions 6. The crank spindle 1 further includes apertures 3, 4, 7, 8, 9 and 10 respectively, such intended to allow for torque sensors, angular position sensors and voltage generator, carried by the power measuring apparatus and to be described later, to protrude therethrough.

Preferably the aperture 3 will allow an angular position sensor or the like to protrude therethrough from a power meter cartridge 30 (FIG. 4) to be housed within the hollow crank spindle 1, whilst the aperture 4 will allow for a wire coil element for a voltage generator or the equivalent making up part of said power meter cartridge 30 to protrude therethrough. The aperture 7 is adapted to extend through the hollow spindle 1 itself and part of one of the dogs or protrusions 6 thereof as shown, to allow for a torque sensor to protrude therethrough for purposes of measuring torque, of the left leg of the cyclist, when acting against the direction of normal pedalling, whilst aperture 8 will allow for measuring of the torque of that same left leg of the cyclist in the direction of pedalling. Apertures 9 and 10, in like manner, will allow for torque sensors to protrude therethrough for measuring torque of the right leg of the cyclist against and in the direction of pedalling respectively.

In accordance with the drawings a chain ring spider 12, adapted for use as a power take-off means and to which chain rings may be attached in any suitable manner and using any suitable means, is mounted on the crank spindle itself and is associated therewith by way of interaction of dogs 13 provided on the chain ring spider 12, substantially complementary with the dogs 6 on the flange 5 of the crank spindle 1, in combination with an adapter 21. In use the dogs 13 of the chain ring spider 12 interconnect with the dogs 6 of the crank spindle 1 itself. The chain ring spider 12 further includes, on the side thereof remote from the dogs 13, a further plurality of dogs 16 adapted to allow for interconnection with the right hand adapter 21.

At least one of the dogs 13, 16 provided on each side of the chain ring spider 12 includes cutaway portions 14, 15, 17, 18 into which, in use, can protrude torque sensors to be housed within a power measuring device, to be located within the hollow spindle 1, for purposes of measuring torque of both the left and right legs of the cyclist both against and in the direction of pedalling.

19 is an aperture through the spider 12 to enable chain rings (not shown) to be mounted thereto in accordance with known practices.

20 is an aperture through the spider 12, the diameter of which is complementary to the outer diameter of the crank spindle 1, allowing the spider 12 to be mounted thereon and rotate relative thereto.

21 is an adapter to be mounted on spindle 1 and intended, in use, to interconnect, by way of dogs 22 formed thereon, with the dogs 16 of chain ring spider 12 and to which the right-hand crank arm 63 is mounted.

At least one of the dogs 22 of the adapter 21 includes a cutaway 23 into which protrudes a torque sensor for measuring torque of the right leg against the direction of pedalling, while at least another of those dogs 22 includes, as a cutaway 24 into which protrudes a torque sensor for measuring torque of the right leg in the direction of pedalling.

The adapter 21 further includes a plurality of external splines 25 which are adapted to interconnect with complementary splines on the right hand crank arm 63 itself (not shown) so that, when mounted thereon, there is no relative movement therebetween. The adapter 21 is hollow, having an aperture 26 extending therethrough, the diameter of which aperture 26 is complementary to the outer diameter of the crank spindle 1, allowing the adapter 21 to be mounted thereon and rotate relative thereto.

Preferably an annular fixing means 27 is provided, such to be securely affixed to the crank spindle 1 so as to allow for rotation of the adapter 21, spindle 1 and spider 12 relative to one another.

In use the spider 12 is mounted on spindle 1 so that the dogs 6 of the spindle 1 and the dogs 13 of the spider 12 interconnect, with there existing a gap 28 (FIG. 3) between the interconnecting dogs 6 of the spindle 1 and dogs 13 of the spider 12, which gap 28 allows a limited amount of movement therebetween.

The right hand adapter 21 is mounted on spindle 1 so that the dogs 22 of that adapter 21 and the dogs 16 of the spider 12 interconnect, with a gap 29 (FIG. 3) existing between the interconnecting dogs 22 of the adapter 21 and the dogs 16 of the spider 12, such gap 29 allowing a limited amount of movement therebetween.

The annular fixing means 27 preferably is press-fitted or mounted on the spindle 1 so that it firmly holds together the spindle 1, spider 12 and adapter 21, allowing them to move rotationally relative to one another by a limited amount by virtue of the gaps 28, 29 which exist between the respective sets of dogs, but not to move axially relative to one another.

Turning now to FIG. 4 there is shown therein a power meter cartridge 30, to be located in accordance with the invention within the spindle 1, which cartridge 30 includes the following as principal components:

a rechargeable battery or the like power source 31, a cap 32 for retaining the battery 31 in place and an enclosure 33 for accommodating the electronics for:

(i) measurement of torque, angular position and cadence;

(ii) calculation of power, angular velocity and angular acceleration;

(iii) voltage regulation and battery charging; and

(iv) a wireless transceiver.

In the preferred embodiment shown 34 is an angular position sensor element, preferably in the form of a Hall Effect sensor, which interacts with a multi-pole ring magnet 58 to determine the angular position of the crank arms and is mounted on a shaft 40 (to be described later).

35 is a wire coil element, preferably consisting of a multi-turn wire coil that interacts with the multi-pole ring magnet 58 to generate an electro-motive force and is mounted on a shaft 40.

36 is a left hand torque sensor element, which consists of a torque sensor mounted on a shaft which senses torque applied to the left-hand crank arm against the direction of pedalling.

37 is a left hand torque sensor element, which consists of a torque sensor mounted on a shaft which senses torque applied to the left-hand crank arm in the direction of pedalling.

38 is a right-hand sensor element, which consists of a torque sensor mounted on a shaft which senses torque applied to the right-hand crank arm against the direction of pedalling, whilst 39 is a right-hand torque sensor element, consisting of a torque sensor mounted on a shaft which senses torque applied to the right-hand crank arm in the direction of pedalling.

40 is a shaft adapted to engage the angular position sensor 34, wire coil element 35 and torque sensor elements 36, 37, 38 and 39 respectively, whilst 41 is a lever connected to the shaft 40, for engaging and disengaging angular position sensor 34, wire coil element 35 and torque sensor elements 36, 37, 38 and 39 respectively.

42 is wiring from torque sensors (36, 37, 38, 39), angular position sensor 34 and wire coil element 35 to the electronics housed within the enclosure 33.

43 are element springs intended to control the engaging and disengaging movement of the torque sensors (36, 37, 38, 39), angular position sensor 34 and wire coil element 35 as and where necessary. 44 are cams or the like means for engaging and disengaging the torque sensors 36, 37, 38, 39, angular position sensor 34 and wire coil element 35.

41 a and 44 a represent a lever and a cam means positioned to engage torque sensors, angular position sensor and wire coil elements, whilst 41 b and 44 b are a lever and a cam means positioned to disengage torque sensors, angular position sensor and wire coil elements.

45 is a transducer bridge for each torque sensor which produces a differential voltage due to the strain produced by the torque being applied to the crank arm.

46 is a differential amplifier for each torque sensor to amplify the voltage variations.

47 is an analogue-to-digital converter for each torque sensor to digitise the output voltage from the differential amplifier 46.

48 is a differential amplifier to amplify the voltage output from the angular position sensor 34.

49 is an analogue-to-digital converter to digitise the output voltage from the angular position sensor differential amplifier 48.

50 is a bridge rectifier to rectify the voltage generated by the interaction of the wire coil element 35 and the multi-pole ring magnet 58.

51 is a voltage regulator to regulate the output voltage from the bridge rectifier 50.

52 is a trickle charger to charge the battery 31.

53 is a microprocessor which receives digital signals from the torque sensors and angular position sensor and calculates the LH power (+) and (−), RH power (+) and (−), angular position, angular velocity, angular acceleration and cadence.

54 is a transceiver and antenna which receives a signal from the microprocessor 53 with information of power, angular position, angular velocity, angular acceleration and cadence and transmits the information to a bicycle computer. The transceiver 54 may also receive a signal from the bicycle computer to calibrate the torque sensor zero reference, adjust the sensitivity slope of any of the torque sensors or perform diagnostics on the power meter electronics.

Turning now to FIG. 7, there is shown therein a left-hand spindle bearing adapter 55 for rotational mounting of the crank spindle 1 to the bicycle frame (not shown). The adapter 55 is hollow with a centrally disposed aperture 56 for rotational mounting of the spindle 1, and has a diameter that is complementary with the outer diameter of the spindle 1. A hollow crank spindle cover 57 is provided to afford water and dust-proofing for the spindle 1 as well as to provide a mounting for the multi-pole ring magnet 58 referred to earlier.

59 is a right-hand spindle bearing adapter for rotational mounting of the spindle 1 to the bicycle frame (not shown), such also being hollow with a substantially centrally disposed aperture 60.

In accordance with the invention the power meter cartridge 30 is mounted in the assembled unit by inserting it into the hollow spindle 1. Alignment grooves (not shown) ensure correct alignment of the two parts so that the torque sensor elements 36, 37, 38, 39, angular position sensor element 34 and wire coil element 35 in the power meter cartridge 30 align with their respective apertures in the spindle 1.

The torque sensor elements 36, 37, 38, 39, angular position sensor element 34 and wire coil element 35 are depicted by 61 in their respective disengaged position.

The power meter functions as follows.

By turning lever 41 the cams 44 push the torque sensor elements 36, 37, 38, 39, angular position element 34 and wire coil element 35 through their respective apertures in the spindle 1. The torque sensor elements 36, 37, 38, 39 protrude into the space made by the cutaway dogs 7, 8, 14, 15, 17, 18, 23 and 24. The cross-sectional dimension of the torque sensor elements 36, 37, 38, 39 and the cutaway dogs still enable limited movement between the spindle 1, spider 12 and right-hand crank adapter 21 and allow torque to be measured by the torque sensor elements 36, 37, 38, 39.

The angular position sensor 34 and wire coil element 35 protrude into the space above the spindle 1 to come into close proximity with the multi-pole ring magnet 58.

The torque sensor elements 36, 37, 38, 39, angular position sensor element 34 and wire coil element 35 are depicted by 62 in their respective engaged position.

As an alternative to the cross-sectional dimension of the torque sensor elements allowing limited movement between the spindle 1, spider 12 and right-hand crank arm adapter 21 when they are engaged with the cutaway dogs, their cross-sectional dimension may disallow limited movement therebetween. The torque sensors still measure torque. However, by disallowing the said limited movement the crankset is turned into a conventional crankset. In yet another embodiment altogether the elements which engage with the cutaway dogs may not have sensors mounted thereto. Instead, their cross-sectional dimension may be such that they serve purely as a lock-up mechanism when engaged with the cutaway dogs.

The power meter the subject of the present application utilises or relies for its effectiveness on the limited movement capability of the crankset of the type referred to in the present applicant's U.S. patent application Ser. No. 11/696,516, which recites an arrangement wherein the respective right and left crank arms 63, 64 have a limited degree of movement relative to the chain ring spider 12. In an especially preferred embodiment that limited degree of movement between the chain ring spider 12 and the respective left and right crank arms 64, 63 is achieved by utilising, for purposes of interconnection, arrays of dogs or the like projections which have a small amount of rotational play or movement therebetween. In accordance with the present invention it is those surfaces between such interconnecting dogs which are employed for purposes of torque measurement.

To be more specific, located between each of the interconnecting dogs may be an element, of a substantially complementary shape, having one or more torque sensors or the like attached thereto. The arrangement is such that, even with such elements inserted between associated dogs, there can be expected to remain to be possible a limited degree of movement between the crank arms 63, 64 and the spider 12. In use when a cyclist applies torque, for example, to the right-hand crank arm 63 in the direction of pedalling, that crank arm 63 will rotate only until its movement is stopped/resisted by the opposing dog of the spider 12 and the torque sensor element located therebetween. Such torque sensor element will then measure the torque in the actual direction of pedalling. In a converse situation, when for example torque is applied to the right-hand crank arm 63 against the direction of pedalling, that crank arm 63 will rotate in a reverse direction until its movement is stopped/resisted by the opposing dog of the spider 12 and that torque sensor element located therein. In such a circumstance the torque sensor will measure torque in a direction opposite to that of pedalling. It should be realised that, in like manner, measurement of torque applied to the left-hand crank arm 64, whether in the direction of pedalling or in the reverse direction, may also be measured.

This capability of measuring torque applied in either direction represents an important advantage attributable to the present applicant's arrangement. In accordance with the prior art means were available for detection only of each complete revolution of a crank arm, whereas in accordance with the present applicant's arrangement measurements can be taken at predetermined angular positions during the course of any revolution.

In accordance with the present invention angular position sensors are employed for detection of the angular position of a given crank arm 63, 64 at predetermined locations throughout revolution thereof, with torque being capable of being measured at each such angular position. The present applicant's arrangement therefore allows for an accurate measurement of power being generated to be obtained over each complete crank revolution, for both left and right legs, in the direction of pedalling as well as against that direction. Such a capability is not evidenced by the prior art.

Because angular velocity is also derived at numerous angles throughout the crank revolution, the rate of change of angular velocity can therefore also be derived to give angular acceleration, a measurement not possible with prior art devices.

By measuring torque in the direction of pedalling, as well as against that direction of pedalling, for both left and right legs of the cyclist, as well as angular position of the crank arm 63, 64, then a monitor either mounted on the handlebar of the bicycle or elsewhere on that bicycle may be employed to display, in real time, the exact position of a “dead” zone.

In a preferred embodiment the bicycle computer has a left and right dead zone display, each consisting of an arm that rotates about a centre point that represents the left and right crank arm positions respectively, their rotation being controlled in real time by the angular position sensor signal from the power meter. The end of each rotating arm points at a co-centric circular display that is divided into a number of segments, each segment representing an arc of rotation of the crank arm. As the end of the arm rotates past a segment, the segment will be illuminated as a colour that represents torque in the direction of pedalling, or another colour representing torque against the direction of pedalling.

By measuring data such as left and right power and respective angular position, in both the direction of pedalling as well as against the direction of pedalling, and downloading it from the bicycle computer memory to a personal computer, far more powerful and accurate post-ride analysis is possible than with prior art arrangements.

Preferably the power meter can generate its own voltage by means of a stationary multi-pole ring magnet embedded in the protective cover of the bottom bracket assembly, and a wire coil mounted on an element that rotates with the crank spindle. When the cyclist is pedaling the crank spindle rotates, which causes the wire coil to move past the multi-pole ring magnet and produce an electro-motive force across its ends. The electro-motive force is used to provide voltage that drives the power meter electronics and keeps a battery trickle charged. In contrast thereto, prior art devices obtain their voltage supply solely from a battery to operate the power meter electronics.

The power meter in accordance with the present invention is designed to incorporate the torque sensor elements, the angular position sensor, the wire coil element, electronics, radio frequency transmitter and battery in a cartridge that is adapted to be inserted in the hollow crank spindle 1. The internal surface of the hollow crank spindle 1 is designed to be complementary to that of the cartridge and has apertures appropriately positioned so that the torque sensor elements, angular position sensor and wire coil element can protrude therethrough.

Unlike the prior art devices, where components on the bicycle need to be replaced to mount the power meter, the cartridge in accordance with the present invention is simply inserted in the hollow crank spindle and the torque sensor elements, angular position sensor and wire coil element are engaged by turning a lever on the cartridge. There is no need for an experienced mechanic for purposes of installation, nor are any special tools required to insert the cartridge.

Turning now to the embodiment of FIGS. 11 to 15 inclusive, FIG. 11 shows a hollow crank spindle 101 adapted, in use, to be associated with/connected to apposed crank arms of a given bicycle. As with the embodiment of FIGS. 1 to 10 the spindle 101 includes, at one end thereof, a splined section 102 to which the left-hand crank arm may be attached, a plurality of apertures 103, 104, and a peripheral flange 105 having a plurality of dogs 106 disposed at spaced-apart locations around the circumference therefor. The apertures 103, 104 are intended to have extending therethrough an angular position sensor element and a wire coil element for a voltage generator respectively. The dogs 106 are adapted, in use, to co-operate with/interconnect with dogs 114 provided on the chain ring spider 112 (FIG. 12).

As shown in FIG. 12 the chain ring spider 112 includes an aperture 113 enabling chain rings (not shown) to be mounted thereon. As with the embodiment of FIGS. 1 to 10, a fixing means in the form of an annular ring 27 is adapted, in use, to be securely affixed to crank spindle 101 so as to allow for limited rotation of the right crank arm 63, spindle 101 and spider 112 relative to one another. The spider 112 includes a plurality of dogs or the like protrusions 114 for co-operation/interconnection with complementary dogs 115 of right-hand crank arm 63. The dogs 106 of spindle 101, 114 of spider 112 and 115 of right-hand crank arm 63 each include a plurality of torque sensor members, generally designated 110, 120, 130 for measuring torque generated by left-hand crank arm 64 and by the right-hand crank arm 63 in the direction of pedalling and against the direction of pedalling, respectively.

With regard to FIG. 14, such is a cross-sectional view of the dogs 106, 114 and 115 of the spindle 101, spider 112 and right-hand crank arm 63 respectively. Also shown therein is the plurality of torque sensors, designated a to p, affixed to dogs 106, 114 and 115 respectively in any suitable manner and using any suitable means. The leads on these torque sensors (not shown) are fed through apertures (not shown) in the hollow crank spindle 101 and terminate on electrical contacts which are located within the spindle 101 or, in the alternative, in the power cartridge 30.

The power meter in accordance with this embodiment functions in like manner to that of the embodiment of FIGS. 1 to 10 inclusive, as set out earlier in this specification, although not specifically shown in the drawings. With this embodiment both the angular position sensor and wire coil elements are operated by means of a shaft, cam and lever, to extend the angular position sensor and wire coil element close to a multi-pole ring magnet, or to retract those elements back into the cartridge 30 itself. As with the earlier embodiment, by extending the angular position sensor and wire coil element into their respective positions, the angular position sensor can measure angular position (using a Hall effect device for example), whilst the wire coil element can generate an electromotive force for voltage generation.

With this embodiment the torque sensors 110 associated with the spindle 101 measure torque produced by one leg of the cyclist, the torque sensors 130 associated with the right crank arm 63 measure torque produced by the other leg, whilst those torque sensors 120 associated with the chainring spider 112 indicate whether the torque is applied (by each leg) in either the direction of pedalling or against that direction.

In the especially preferred embodiment of FIG. 15 a torque sensor is affixed to each interconnecting dog 106 of the spindle 101, 114 of spider 112 and 115 of right-hand crank arm 63. The torque transducers are grouped and connected in a transducer bridge 145 which produces a differential voltage due to strain produced by the torque being applied to the crank arms.

In, this drawing Vin is the input voltage to each transducer bridge configuration, VLeft is the output voltage from the transducer bridge consisting of torque sensors a, e, i and m that is produced by a force applied to the left-hand crank arm, while VRight is the output voltage from the transducer bridge consisting of torque sensors c, g, o and k produced by a force applied to the right-hand crank arm.

VSpiderGroup1 is the output voltage from the transducer bridge consisting of torque sensors b, f, j and n as produced by torque transferred thereupon by the force applied to the left-hand crank arm and/or right-hand arm.

VSpiderGroup2 is the output voltage from the transducer bridge consisting of torque sensors d, h, p and l as produced by torque transferred thereupon by the force applied to the left-hank crank arm and/or right-hand crank arm.

VSpiderGroup1 serves to determine whether torque applied to the left-hand arm is in the direction or against the direction of pedalling, while VSpiderGroup2 serves to determine whether torque applied to the right-hand crank arm is in the direction or against the direction of pedalling.

In practical terms the power measuring apparatus in accordance with the present invention exhibits a number of advantages over the prior art, as referred to hereinafter.

Firstly, the cyclist has the benefit of being able to measure the individual power of the left and right leg both in the direction of pedalling as well as against the direction of pedalling, hence allowing the cyclist to fully understand the physical performance of each leg and the ability thereof to work together synchronously to maximise efficiency and power delivery. When one leg is not providing torque to the crank arm to contribute to driving the bicycle forwards, for instance on the upstroke, it is being carried by the other leg pushing on the downstroke. The leg being carried on the upstroke is reducing the power the downstroke leg is producing to propel the bicycle. Because the upstroke leg is consuming power from the downstroke leg, it is considered to be generating negative power. Knowing how much negative power each leg generates is valuable information to the cyclist to train to eliminate it.

Prior art devices include a sensor that can only detect each complete revolution of the crank arm and measure the time this takes. The derived angular velocity is therefore an average per complete crank revolution. Therefore the calculated power is a function of average angular velocity. When pedalling a bicycle, especially when standing up, angular velocity is not constant. The device in accordance with the present invention measures angular velocity at numerous angles throughout the crank revolution, and torque is measured at each angle. Therefore the calculated power at each measurement angle is instantaneous and not an averaged reading as with the prior art, and the cyclist has visibility of the peaks and troughs in power during each crank revolution.

Since prior art devices only measure angular velocity for a complete crank revolution, said devices cannot calculate the angular acceleration of the crank arm during each crank revolution. Angular acceleration is an important measurement, especially for a track cyclist who has to accelerate to race pace from a standing start. With the device of the present invention, by having access to knowledge of instantaneous power and angular acceleration the track cyclist can scientifically work out the best gear ratios to use for his/her physical capability and maximum performance.

The capability for real time display of the left and right leg “dead” zones shows the rider precisely where the “dead” zones start and end. This indicates graphically to the cyclist whether the “dead” zone is occurring at the transition of power from one muscle group to another, or whether it is a particular, muscle group that is weak or fatigued. The cyclist can also correlate what he/she sees on the display with the bumps felt through the backward movement of the limited movement crank arm. The visual display provides an added sense to train the proprioceptors in the brain to eliminate “dead” zones. Prior art arrangements cannot measure or display “dead” zones.

The science of human performance is extremely important in the world of professional sport, and especially so with regard to cycling, which requires incredible levels of endurance for races that can last for a number of weeks. Any improvement, no matter how slight, in pedalling technique and physical ability can mean a greater chance of success. The more accurate and extensive the information a cyclist is able to measure about cycling ability, the better the cyclist will be able to train and correct any detected weaknesses whereby to improve performance.

Having an integrated voltage generator, the power meter in accordance with the present invention is self-sufficient, with its own source of electrical power, and therefore only needs a small battery to supply the electronics when the power meter is idle, after which the voltage generator will take over powering the electronics and trickle charging the battery when pedalling. A real advantage of having its own voltage generator is that the torque and angular velocity can be measured at numerous angles during each crank revolution and transmitted to the bicycle computer over a wireless link without concern for the battery going flat.

The power meter in accordance with the present invention is designed as a cartridge to incorporate the torque sensor elements or contacts thereof, the angular position sensor, the wire coil element, electronics, radio frequency transmitter and battery. Because of its complementary shape with the hollow crank spindle 1 or 101, to mount it to the bicycle only requires it to be inserted in the hollow crank spindle. Turning a lever on the cartridge enables the sensory elements, to be moved into position. Unlike with the prior art arrangements, no tools or special knowledge are required to do this, only the very basic of practical skills to push the cartridge into the hollow crank spindle 1 and turn a lever.

Finally, it is to be understood that the foregoing description refers merely to preferred embodiments of the invention, and that variations and modifications will be possible thereto without departing from the spirit and scope of the invention, the ambit of which is to be determined from the following claims. 

1. An apparatus for measuring and monitoring the torque exerted by a cyclist during pedalling of a human-powered machine, said apparatus further including a cartridge or the like which is adapted, in use, to be releasably retained within a hollow spindle of said machine, said further apparatus including one or more sensor elements for progressively sensing and generating signals, during rotation of a crankshaft of said machine, which signals are indicative of the angular position of said the or each crank arm of said machine and/or the torque applied thereto.
 2. The apparatus as claimed in claim 1, adapted to be connected to a power take-off device of said machine, wherein said machine is a bicycle having a crankshaft or spindle disposed within a frame and a crank arm associated with each free end of said crankshaft, wherein at least one of said crank arms is adapted to be able to rotate to a limited extent relative to said power take-off device.
 3. The apparatus as claimed in claim 2, wherein torque applied to the or each crank arm may be measured in either the direction of, or against the direction of, pedalling of the cyclist.
 4. The apparatus as claimed in claim 3, wherein said hollow spindle includes a splined section at or in the vicinity of one free end thereof, to which one end a first crank arm of said bicycle is adapted to be releasably attached, and wherein said hollow spindle further includes, at a location spaced from the other free end thereof, a peripheral flange and a plurality of dogs or the like protrusions associated therewith disposed around the periphery of the spindle, said dogs of said spindle being adapted, in use, to co-operate, to a limited extent of movement or to close tolerance, with complementary dogs or the like protrusions of a chainring spider of said bicycle, which is adapted to be located on and co-operate with said hollow spindle, wherein said spindle and said chainring spider are, in turn, adapted in use to be releasably attachable to a second crank arm of said bicycle, said chainring spider further including at least one aperture for chainrings.
 5. The apparatus as claimed in claim 4, wherein said spindle, chainring spider and second crank arm are held together by a fixing means.
 6. The apparatus as claimed in claim 5, wherein said fixing means is a threaded or press-fitted annular ring.
 7. The apparatus as claimed in claim 6, wherein said crank arm is adapted to co-operate with said spindle and includes a plurality of dogs or the like protrusions adapted, in use, to co-operate with said dogs of said chainring spider, to a limited extent of movement or to close tolerance.
 8. The apparatus as claimed in claim 7, including adapter means to be associated with said spindle, wherein said adapter means includes a plurality of dogs or the like protrusions disposed around the periphery thereof, said dogs of said adapter means co-operating with said dogs of said chainring spider, said adapter means being releasably affixed to said second crank arm.
 9. The apparatus as claimed in claim 8, including a further adapter means, to be mounted within the frame of said bicycle, to allow for rotation of the assembly of said spindle, chainring spider and second crank arm.
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 18. The apparatus as claimed in claim 9, wherein said hollow spindle of said bicycle includes a plurality of apertures extending therethrough, said apertures intended to have protruding therethrough means for connection with one or more of said sensor elements, and wherein said sensor elements include an angular position sensor and a voltage generator.
 19. The apparatus as claimed in claim 18, wherein one or more of said dogs of said spindle has a torque sensor associated therewith.
 20. The apparatus as claimed in claim 19, wherein one or more of said dogs of said chainring spider has a torque sensor associated therewith.
 21. The apparatus as. Claimed in claim 20, wherein one or more of said dogs of said second crank arm has a torque sensor associated therewith.
 22. The apparatus as claimed in claim 21, wherein each said torque sensor is affixed to an associated dog of said spindle/chainring spider and/or said second crank arm.
 23. The apparatus as claimed in claim 22, wherein wires of said torque sensors protrude through apertures provided in said spindle and terminate on electrical contacts located internally of said spindle.
 24. The apparatus as claimed in claim 23, wherein said cartridges include, spread apart around the periphery thereof, electrical contacts complementary to those of said spindle.
 25. The apparatus as claimed in claim 24, wherein said angular position sensor and wire coil element are operated by means of a shaft, cam means and lever whereby to extend said angular position sensor and wire coil element into juxtaposition with a multi-pole ring magnet or retract said angular position sensor and wire coil element into said cartridge.
 26. The apparatus as claimed in claim 25 wherein, upon extension of said angular position sensor and wire coil element, said angular position sensor measures angular position and said wire coil element generates an electromotive force for voltage generation.
 27. The apparatus as claimed in claim 26, wherein said torque sensors associated with said spindle measure torque produced by one leg of the cyclist, said torque sensors associated with the second crank arm measure torque produced by the other leg of said cyclist, and said torque sensors. associated with said chainring spider indicates whether torque is applied, by each leg, either in or against the direction of pedalling.
 28. The apparatus as claimed in claim 1, wherein said cartridge is of a substantially complementary shape to said hollow spindle and is housed within said spindle.
 29. The apparatus as claimed in claim 28, including a hollow crank spindle cover which includes a multi-pole ring magnet.
 30. The apparatus as claimed in claim 1, wherein said cartridge further includes a power source, preferably re-chargeable, an enclosure for accommodating electronic circuitry, and a wireless transceiver.
 31. The apparatus as claimed in claim 30, wherein said electronic circuitry includes: a transducer bridge, amplifier and analogue to digital converter for said torque sensors; an amplifier and analogue to digital converter for said angular position sensors; a bridge rectifier, voltage regulator and trickle charger for voltage generation; and a microprocessor. 